This invention relates in general to battery housing structures, and more particularly, to battery housings and battery packs used by portable electronic devices.
Portable electronic devices, such as so-called laptop computers for example, by their nature require a portable source of power. Battery packs composed of either rechargeable or non-rechargeable cells provide such a portable source of power.
To reduce the total weight of battery packs which usually tend to be relatively heavy, it is desirable to make the housings for such battery packs of light-weight plastic materials. Although such light-weight plastic materials are desirable for battery housing applications due to their low weight, these plastic materials are also highly desirable due to their electrically insulative properties. Unfortunately however, when a battery housing fabricated from such a material is made relatively thin, the resultant battery housing often exhibits undesirably low structural integrity. Battery packs which exhibit low structural integrity are potentially dangerous and should be avoided in portable electronic applications.
Many portable battery packs are fabricated with parallelepided (rectangular-sided) housings divided into two halves, each half being formed from relatively thick injection molded thermoplastic materials such as ABS (acrylic butyl styrene) plastic and polycarbonate. Conventional cylindroidal voltaic cells are placed inside the rectangular housing of such a battery pack. The interior plastic walls of the housing are shaped to hold the cells. With a significant portion of the volume of the battery pack being taken up by the rectangular plastic housing itself and the open spaces between the cells, the energy density of such battery packs tends to be relatively low, whereas the weight of the structure tends to be relatively high. Another disadvantage of this battery housing arrangement is that the battery pack tends to be relatively easy to break and fracture upon dropping.
As discussed above, parallelepiped or rectangular battery housings are typically adapted for housing cylindroidally-shaped voltaic cells. However, with the advent of so-called "flat cells" (battery cells which exhibit a thin rectangular profile), a high strength, low weight battery housing for such cells becomes very desirable.